U.S. Geological Survey --------------------------------------------------------------------------- Metadata for HUC250 Table of Contents Identification_Information Abstract Purpose Supplemental Information Data_Quality_Information Spatial_Data_Organization_Information Entity_and_Attribute_Information Detailed Description Overview Distribution_Information Metadata_Reference_Section --------------------------------------------------------------------------- Identification_Information Citation_Information Originator: Alhadeff, S. Jack Publication_Date: 1996 Title: Hydrologic Units of Georgia Edition: 2.0 2.1 Datum change from 1927 to 1983 (North American Datum of 1983) Data Re-projected using North American Datum (NAD83) - September 2000 Series_Information Series_Name: Digital Data Series Publication_Information Publication_Place: Atlanta, GA Publisher: U.S. Geological Survey Online_Linkage: http://csat.er.usgs.gov/statewide/layers/huc250.html Scale_Denominator: 250000 Description Abstract The Geographic Information Retrieval and Analysis System (GIRAS) was developed in the mid 70s to put into digital form a number of data layers which were of interest to the USGS. One of these data layers was the Hydrologic Units. The map is based on the Hydrologic Unit Maps published by the U.S. Geological Survey Office of Water Data Coordination, together with the list descriptions and name of region, subregion, accounting units, and cataloging unit. The hydrologic units are encoded with an eight- digit number that indicates the hydrologic region (first two digits), hydrologic subregion (second two digits), accounting unit (third two digits), and cataloging unit (fourth two digits). The data produced by GIRAS was originally collected at a scale of 1:250K. Some areas, notably major cities in the west, were recompiled at a scale of 1:100K. In order to join the data together and use the data in a geographic information system (GIS) the data were processed in the ARC/INFO GIS software package. Within the GIS, the data were edgematched and the neatline boundaries between maps were removed to create a single data set for the conterminous United States. The 1:100,000 scale digital boundary of the State of Georgia derived from the 1990 precensus/TIGER line files was used to extract a Georgia Hydrologic Unit map. Keywords: HUC, GIRAS, Hydrologic Units, 1:250, Georgia, River Basins Purpose Applications that use this data This data set was compiled originally to provide the National Water Quality Assessment (NAWQA) study units with an intermediate- scale river basin boundary for extracting other GIS data layers. The data can also be used for illustration purposes at intermediate or small scales (1:250,000 to 1:2 million). Intended use of data See the above statement Supplemental_Information Procedures_Used The data was received as compressed giras tar files representing either a 1:250,000-scale (1:250K) quadrangle or a 1:100,000-scale (1:100K) quadrangle. Each file was named after its respective quadrangle. A coverage of 1:250k quadrangles was used to divide the country up into four sections and get a list of names for each section. Using GIRASARC2, an aml designed to create an ARC/INFO data set (coverage) from a GIRAS file and a corresponding neat line coverage, it was quickly discovered that many of the quad names were to long for the program (i.e. sault_saint_marie) and a generic naming system for files and coverages was incorporated. In 1 of 10 cases, the name of the quadrangle did not correspond with the name of the file. These problems were traced down and corrected (after all four sections were converted there were many files left over...these wound up being all the 1:100k quads which did not have similar names to the 1:250k files). After the files for a given section were all converted into ARC/INFO format, a loop aml was run which copied a coverage and its neatline cover into temporary storage (there was not enough room in info to deal with a large number of files in one directory), attached to that directory, built line topology, and went into the editor, ARCEDIT. In ARCEDIT, the outer edge (original neatline) was selected and deleted and the mathematically-calculated neatline coverage from the GIRASNEAT AML program was copied in using the ARCEDIT GET command. The original neatline was replaced with a calculated neatline because in all cases, the outline of the coverage quad never quite conformed to a "true" neatline causing overlaps and gapes between adjacent maps. The new neatline was connected to the internal arcs where they intersected. Lines which did not quite join the new neatline were extended to the edge with a maximum tolerance of 500 meters. All extensions were made within this tolerance. All arcs which extended beyond the new neatline were clipped off within a 500 meter tolerance as arguments to the CLEAN command into a separate directory. Both the neatline and HUC coverages were deleted from the temporary space, and the program looped to the next coverage. Another program was then run which added an item to the .aat called OUTER, went into INFO, and populated the attribute for all arcs composing the new neatline. This was done by reselecting for the identity of the polygon to the left or right of each arc whose value was "1", the identity of the outer "universe" polygon (reselect lpoly# = 1 or rpoly# = 1 in the .aat and calculated outer to = 1). All coverages were checked for additional dangles and then a MAPJOIN was run using NET as the feature option. Finally, most map edge lines were removed from the MAPJOINed coverage using the DISSOLVE to create a seamless basin coverage with polygons (basins) and arcs (boundaries) with attributes. Quality control methods were applied to the resulting coverage by detecting and fixing node and label errors and remaining neat line arc problems (i.e. long neat lines still in the coverage). Many more problems arose in the western part of the country than in the east. Bordering HUC code disagreements between quads caused a number of cases in which neatlines did not dissolve. These were provisionally corrected for the most part, however there were several cases that required external review and editing to fix, and are now incorporated in the final data set. After all 1:250K sections were completed, the same procedure was run for the handful of 1:100k quads. These were mapjoined with the 1:250k quads to provide more detailed coverage where it was available. A clip using the 1:100,000 scale boundary data derived from the 1990 pre- census TIGER line files created the final product for Georgia. The data was projected from a national Albers (central meridian -96.0) to a State of Georgia Albers (central meridian -83.5) Revisions Revision #1. 10/92 See above for all the details Revision #2. 1/93 Seattle and Bakersfield quadrangles were missing from the composite supplied by Pete Steeves. These were manually pasted in using Arcedit with small tolerances. Labelerrors were remedied and most dangles were removed using the Eliminate command. Revision #3. 12/93. The following changes were made to a 1:250,000-scale version derived from National Mapping Divisions Geographic Information Retrieval and Analysis System (GIRAS) data. The discrepancies in the hydrologic unit codes (HUCs) in California were changed because the California State Hydrologic Unit Map (HUM) was revised in 1978 but the 1:250,000-scale digital dataset was not. This has been reviewed by Bill Battaglin, Doug Nebert, and Paul Kapinos and is noted under Reviews (#6 below). The areas in which the HUC labels were incorrect in California were 180701, 180702, 180703, 180600, 180300, and 180400. Boundaries were added in 180702 and 180600 from the 1:2 million source. Along the Oregon/California border, a boundary was added in 180102. In Wyoming, a boundary was added in 100902 from the 1:2 million source. Labels were corrected in these HUCs to reflect state updates, and where necessary, to add new labels to the newly-drawn boundaries. Map edges were manually removed in Arkansas, California, and along the Oregon/California border. After the changes were made and saved in Arcedit, the build and clean commands were executed, followed by labelerrors. Three polygons had duplicate labels and were corrected. The labels were centered in the polygons by the centroidlabels command. Verification of the coverage was done by the describe command. Revision #4. 3/94. The NAMES file was added to the data set and its attributes were defined in the ATT file of the documentation. This table is a lookup table to correlate the 8-digit numbers with verbose names officially assigned to the basins. Revision 2.0 Revision #5. 12/96. A DNRBASIN Item was added to assist in delineating Major River Basins used/named by U.S. Geological Survey and Georgia Department of Natural Resources. There are 14 Major River Basins as defined by the Georgia Department of Natural Resources 1995 publication of Water Quality of Georgia Streams 1994-1995 (cover illustration). Each 8 digit Hydrologic Unit was identified and tagged with an appropriate Major Basin Name (DNRBASIN). Due to the labeling of units of the Aucilla and Apalachicola by Georgia Department of Natural Resources as part of the Ochlockonee basin, the label for the Ochlockonee basin will be "OCHLOCKONEE AND OTHERS". MAJOR RIVER BASINS IN GEORGIA Major River Basin (DNRBASIN) Area (square meters) ---------------------- -------------------- ALTAMAHA 7387750144.000001 CHATTAHOOCHEE 15470538368.000004 COOSA 11996547328.000002 FLINT 21879261312.000006 OCHLOCKONEE AND OTHERS 3970577464.000001 OCMULGEE 15762244864.000002 OCONEE 13813148160.000000 OGEECHEE 15057873920.000002 SAINT_MARYS 1664592512.000000 SATILLA 10864442368.000001 SAVANNAH 14880123898.039065 SUWANNEE 14418455040.000001 TALLAPOOSA 1684495232.000000 TENNESSEE 3897125100.000000 MAJOR RIVER BASINS BY HYDROLOGIC UNIT CODE Major River Hydrologic Basin (DNRBASIN) Unit Code ----------------------- --------- ALTAMAHA 03070107 ALTAMAHA 03070106 CHATTAHOOCHEE 03130001 CHATTAHOOCHEE 03130002 CHATTAHOOCHEE 03130003 CHATTAHOOCHEE 03130004 COOSA 03150101 COOSA 03150102 COOSA 03150105 COOSA 03150103 COOSA 03150104 FLINT 03130005 FLINT 03130006 FLINT 03130007 FLINT 03130009 FLINT 03130008 FLINT 03130010 OCHLOCKONEE AND OTHERS 03120002 OCHLOCKONEE AND OTHERS 03110103 OCHLOCKONEE AND OTHERS 03120003 OCHLOCKONEE AND OTHERS 03120001 OCHLOCKONEE AND OTHERS 03130011 OCMULGEE 03070103 OCMULGEE 03070104 OCMULGEE 03070105 OCONEE 03070101 OCONEE 03070102 OGEECHEE 03060201 OGEECHEE 03060202 OGEECHEE 03060203 OGEECHEE 03060204 SAINT_MARYS 03070204 SATILLA 03070201 SATILLA 03070202 SATILLA 03070203 SAVANNAH 03060102 SAVANNAH 03060104 SAVANNAH 03060101 SAVANNAH 03060103 SAVANNAH 03060105 SAVANNAH 03060103 SAVANNAH 03060106 SAVANNAH 03060108 SAVANNAH 03060109 SAVANNAH 03050208 SUWANNEE 03110202 SUWANNEE 03110204 SUWANNEE 03110203 SUWANNEE 03110201 TALLAPOOSA 03150108 TENNESSEE 06020001 TENNESSEE 06010202 TENNESSEE 06020003 TENNESSEE 06020002 TENNESSEE 06030001 Revsion 2000 - Datum change from 1927 to 1983 (North American Datum of 1983) Reviews_Applied Peer review, 10/18/93, Bill Battaglin, USGS-WRD, Lakewood, Co, memo to Doug Nebert: ---------------------------------------------------------------------- "I have completed a review of the 1:250,000 scale hydrologic units coverage (HUC) and found the digital data and metadata to be of high quality. I have a few suggested improvements to the digital data and to the documentation. Below is a summary of the methods I used to check feature accuracy in the digital data base and the problems I found. Digital Features: The line work for the HUC coverage was checked against the line work from: (1) the 1:2,000,000 HUC coverage by plotting both data sets out on one large graphic (about 1:3,000,000). No major discrepancies were found except in coastal areas where the 1:2,000,000 scale coverage had more detail than the 1:250,000 scale coverage. (2) line work from 1:24,000 scale digitized drainage basins in Colorado, Illinois, and New Jersey. The match was generally good with departures generally less than 2500 meters. The biggest departures were in Colorado and were as large as 4000 meters. (3) line work from the 1:2,000,000 scale rivers coverage for the USA by plotting both data sets out on one large graphic (about 1:3,000,000). In general the nesting of streams in HUCs was good and HUC boundaries inter- sected steams at stream intersections. In some places (SE New Mexico, SE California and NW Utah), the streams coverage does not match the HUC coverage that well, but this could easily be because of the unusual nature of streams in these areas or because of inaccuracies in the streams coverage. (4) line work from 1:100,000 scale streams from Colorado, Illinois, and Kansas. The nesting of streams in HUCs was very good. Stream arcs for the most part did not cross HUC arcs except at stream intersections. The error (distance from intersection to HUC line) between HUC lines and stream intersection was less than 500 meters at all intersections checked (about 25). Problems with Line work: (1) There was a very large number of very short arcs in the coverage (3211 Lt 1000 meters long and 1729 Lt. 100 meters long). Most of these arcs were internal (did not border on outside polygon) and coded as 250k edges(3) (almost 3000) but some were 250k (2) lines and one was a 2m dlg (4). Arcs with lengths of less than 100 meters (maybe even less than 1000 meters) are difficult to deal with when editing subsets of the coverage, and they also add to the overall size of the database. I know many of these lines were created in the process of edgematching the quads, but I think the informa- tion content of these very short arcs is less valuable than the hassle and overhead involved in keeping them in the coverage. (2) The edit distance for the coverage was set to a very small value. This may have been required for earlier processing, however, it makes the finished coverage difficult to work with. I had to reset the edit distance to a larger value when I wanted to select arcs in ARCEDIT interactively. This, of course, will be one of the things users will want to do with the new HUC coverage. Polygon labels/attributes: (1) Label point accuracy was checked by making a point cover of polygon labels from the 1:2,000,000 HUC coverage and then doing an identify of those points in the 1:250,000 scale HUC polygon. This procedure looked for both new or missing polygons, and was also used to check attribute values. I also dissolved both coverages by accounting unit and compared the number and location of remaining polygons. Problems with labels/attributes: (1) I discovered a total of 649 places where the HUC codes from the label point of the 1:2,000,000 coverage did not match the HUC code for the 1:250,000 HUC polygon that it fell within. As you had indicated in the documentation, there were a lot of differences in California. The 2m HUC had lots of label points resulting from islands, bays, and estuaries that are not included in the 1:250,000 scale HUC coverages. In other places the polygons seemed to be the same but the HUC codes were different. For example HUC 18020111 in the 1:2,000,000 coverage is coded as HUC 18020023 in the 1:250,000 coverage. There were also many differences in the Great Lakes. It seems odd that the 1:2,000,000 coverage should have more detail with regard to coastal features than the 1:250,000 scale coverage has. There were also internal polygon label differences in Minnesota (7100001 in 250k, 70200001 in 2m), Colorado (10090204 in 250k, 10180007 in 2m), Illinois (mistake in the 2m HUC I think), and Louisiana (11140203 in 250k, 11140202 in 2m). Texas and Florida also have a few that look like they should be checked. (2) The dissolved 1:2,000,000 coverage contained 350 accounting unit polygons while the dissolved 1:250,000 HUC coverage only contained 177. There were large differences in the way the Accounting unit polygons looked in the Great Lakes Region, and in parts of California, Wyoming, and Florida. Again, many of the differences result from the use of a cruder coastline in the 1:250,000 scale HUC coverage. Coverage Documentation: The coverage documentation was reviewed both editorially and for overall completeness. The documentation was editorially sound and did not need any corrections. Problems with the Documentation: (1) The redefined items in the pat file were not defined in the data dictionary portion of the documentation file. (2) The complete reference to the source material for the data is not in the documentation file." Response to Peer review by Bill Battaglin, 1/5/93, Doug Nebert, USGS-WRD, Rest ------------------------------------------------------------------------------ Data were reviewed for attribute accuracy against a 1:2million base through random audit of polygon features. Line attributes were verified by symbol- ization on the screen. Regions were shaded in to verify correct polygon values for HUC at the Hydrologic Region level. Documentation was updated. The short arcs along the quadrangle boundaries were kept in the data set due to the importance of maintaining as much original information as possible. Basin codes were updated and additional erroneous neatlines removed Colleague review May 1, 1996 by Keith McFadden and Jonathan Musser. Digital data was reviewed with respect to positional accuracy, contextual accuracy, attribute accuracy, topological consistency, and metadata content. Join HUC250.NAMES to digital spatial data (PAT). Done. Fix tics. Done. Delete non-Georgia references. Left in for historical purposes. Approved by Tim Hale, Georgia District Chief, May 3, 1996. Addition of BASIN item (Major River Basins) by Martin Leckie. Checked and reviewed by Eric Steinnagel and Jack Alhadeff all of the U.S. Geological Survey Center for Spatial Analysis Technologies. Change of BASIN name to DNRBASIN, change of "OCHLOCKONEE" to "OCHLOCKONEE AND OTHERS" due to the inclusion of Aucilla and Apalachicola basins in Georgia DNRs labelling of the Ochlockonee basin. Fixed tables associated with said change. Fixed two spelling errors in new documentation. Jonathan Musser 1/23/97. Related_Spatial_and_Tabular_Data_Sets Any data set which has hydrologic unit codes as part of their data may be able to use this data. Other_References_Cited ______, 1995, Water Quality of Georgia Streams 1994-1995, Environmental Protection Division, Georgia Department of Natural Resources, Atlanta, Georgia. ______, 1990, TIGER/Line Precensus Files, 1990, U.S. Department of Commerce, Bureau of Census, Washington D.C. U.S. Geological Survey, 1990. Land Use and Land Cover Digital Data from 1:250,000- and 1:100,000-Scale Maps. Data Users Guide 4, 33 pp, Reston Virginia. Notes Additional review notes: Peer review, 11/10/93, Doug Nebert, USGS-WRD, Reston, memo to Paul Kapinos: --------------------------------------------------------------------------- "As you are aware, we have several digital versions of the hydrologic unit a 1:250,000-scale version derived from National Mapping Division Geographic Information Retrieval and Analysis System (GIRAS) data as part of their land use mapping program of the 1970s and early 1980s. basin definition and hydrologic unit codes in Southern California and in the San Joaquin valley. The 1974 state map, at 1:500,000-scale agrees with the paper maps are authoritative sources of information, but apparently something changed between the two maps. On a related note, it is worthwhile to mention that the 1:2.5 million-scale depicted there are also the authoritative ones. I would appreciate your review and adjudication of the California hydrologic unit definitions in order for us to publish this digital data set. Please provide a written response (e-mail and paper copy) and marked-up maps as to which basins and boundaries are current." Peer review, 11/29/93, Paul Kapinos, USGS-WRD, memo to Doug Nebert: ------------------------------------------------------------------- "The discrepancies in the hydrologic unit codes (and some boundaries) in the State of California are due to the fact that the California State Hydrologic Unit Map (HUM) was revised in 1978 but the 1:250,000-scale digital data set was not. The events that most likely occurred can be summarized as follows: o The 1:500,000-scale HUMs were published by OWDC over a period of about four years between 1974 and 1978. o The National Mapping Division (NMD) overlaid the hydrologic unit boundaries on their 1:250,000-scale land-use and land-cover map series after each State HUM was completed, and later digitized these boundaries and their respective codes. o In 1978, the State of California asked OWDC to revise the hydrologic unit boundaries and codes in the central valley. o The 1:500,000-scale California HUM was revised and reprinted but NMD was either not informed of the revisions or chose not to revise or redigitize their 1:250,000-scale overlays. o Once all the HUMs were printed (including the 1978 revisions of California and South Dakota), the 1980 1:2.5 million-scale United States wall map was published using the up-to-date (1978) boundaries and codes. Based on the above summary, I would recommend using the boundaries and codes from the 1:2.5 million-scale map and the 1:2,000,000 digital data set. Please be aware that other hydrologic unit boundaries and/or codes may have been revised when individual State HUCs were reprinted by OWDC. I doubt if there has been any attempt to update any of the digital data sets with these changes." Response to Peer Review by Paul Kapinos, Doug Nebert 2/14/94: ------------------------------------------------------------- The areas in question in California were updated to reflect the more current information as contained in the 1:2 million data set. Polygon hydrologic unit codes were updated in the Central Valley and in coastal Southern California. Where necessary, 1:2 million-scale linework was substituted to define the correct basin boundaries where no corresponding information was available at a different scale. Time_Period_of_Content Single_Date/Time Calendar_Date: unknown Currentness_Reference data current as of publication date Status Progress: Approved for release by Tim Hale, Georgia District Chief Maintenance_and_Update_Frequency none planned Spatial_Domain Bounding_Coordinates West_Bounding_Coordinate: -85.60520177 East_Bounding_Coordinate: -80.73842313 North_Bounding_Coordinate: 34.98459988 South_Bounding_Coordinate: 30.33389644 Keywords Theme Theme_Keyword_Thesaurus: None Theme_Keyword: Georgia Hydrologic Units HUC Watershed Place Place_Keyword_Thesaurus: None Place_Keyword: State of Georgia Stratum Stratum_Keyword_Thesaurus: None Stratum_Keyword: Temporal Temporal_Keyword_Thesaurus: None Temporal_Keyword: Access_Constraints none Use_Constraints These data were digitized at a scale of 1:250,000 with some portions of coverage at 1:100,000- and 1:2 million scale. Limitations of the data strictly revolve around this scale input. Use of these boundaries with larger scale data (i.e. 1:24k hydrography) is not recommended as it would be beyond the resolution capabilities of the data set. Point_of_Contact: See Data_Set_Credit U.S. Geological Survey Security_Information Security_Classification_System: None Security_Classification: UNCLASSIFIED Security_Handling_Description: None Native_Data_Set_Environment: dgux UNIX, ARC/INFO version 7.0.4 Cross_Reference Originator: Steeves, Peter and Nebert, Douglas Publication_Date: 1994 Publication_Time: Title: Hydrologic Units of the Conterminous United States, 1:250,000-scale nominal Edition: 1.0 Geospatial_Data_Presentation_Form: Series_Information Series_Name: digital data Issue_Identification: Publication_Information Publication_Place: Reston, VA Publisher: U.S. Geological Survey Other_Citation_Details: Online_Linkage: Larger_Work_Citation: --------------------------------------------------------------------------- Data_Quality_Information Attribute_Accuracy Attribute_Accuracy_Report: See Logical_Consistency_Report: Polygon and chain-node topology present. Completeness_Report no deliberate ommisions Positional_Accuracy Horizontal_Positional_Accuracy Horizontal_Positional_Accuracy_Report: unknown Quantitative_Horizontal_Positional_Accuracy_Assessment: Horizontal_Positional_Accuracy_Value: 120 meters Horizontal_Positional_Accuracy_Explanation: Resolution as reported Vertical_Positional_Accuracy Vertical_Positional_Accuracy_Report: n/a Lineage: See Cloud_Cover n/a --------------------------------------------------------------------------- Spatial_Data_Organization_Information Direct_Spatial_Reference_Method: Vector Point_and_Vector_Object_Information SDTS_Terms_Description SDTS_Point_and_Vector_Object_Type: Point Point_and_Vector_Object_Count: 55 SDTS_Point_and_Vector_Object_Type: String Point_and_Vector_Object_Count: 317 SDTS_Point_and_Vector_Object_Type: GT-polygon composed of chains' Point_and_Vector_Object_Count: 56 --------------------------------------------------------------------------- Spatial_Reference_Information Horizontal_Coordinate_System_Definition Planar Map_Projection: Map_Projection_Name: ALBERS Longitude_of_Central_Meridian: -83.5 Latitude_of_Projection_Origin: 23 Latitude_of_First_Standard_Parallel: 29.5 Latitude_of_Second_Standard_Parallel: 45.5 False_Easting: 0.00000 False_Northing: 0.00000 Geodetic Model Horizontal_Datum_Name: North American Datum of 1983 Ellipsoid_Name: GRS 80 Semi-major_Axis: 6,378,206.4 Denominator_of_Flattening: 294.98 --------------------------------------------------------------------------- Entity_and_Attribute_Information Detailed_Description Entity_Type Entity_Type_Label: HUC250.PAT Entity_Type_Definition: HUC POLYGONS Entity_Type_Definition_Source: GIRAS DATA Attribute: Attribute_Label: ' AREA' Attribute_Definition: Area of polygon in square coverage units Attribute_Definition_Source: Computed Attribute_Domain_Values Enumerated_Domain Enumerated_Domain_Value: Positive real numbers Enumerated_Domain_Value_Definition Enumerated_Domain_Value_Definition_Source: Attribute: Attribute_Label: ' PERIMETER' Attribute_Definition: Perimeter of polygon in coverage units Attribute_Definition_Source: Computed Attribute_Domain_Values Enumerated_Domain Enumerated_Domain_Value: Positive real numbers Enumerated_Domain_Value_Definition Enumerated_Domain_Value_Definition_Source: Attribute: Attribute_Label: HUC250# Attribute_Definition: Internal feature number Attribute_Definition_Source: Computed Attribute_Domain_Values Enumerated_Domain Enumerated_Domain_Value: Sequential unique positive integer Enumerated_Domain_Value_Definition Enumerated_Domain_Value_Definition_Source: Attribute: Attribute_Label: HUC250-ID Attribute_Definition: User-assigned feature number Attribute_Definition_Source: User-defined Attribute_Domain_Values Enumerated_Domain Enumerated_Domain_Value: Integer Enumerated_Domain_Value_Definition Enumerated_Domain_Value_Definition_Source: Attribute: Attribute_Label: ' HUC' Attribute_Definition: HYDROLOGIC UNIT ID Attribute_Definition_Source: GIRAS DATA Attribute_Domain_Values Enumerated_Domain Enumerated_Domain_Value: No restrictions Enumerated_Domain_Value_Definition Enumerated_Domain_Value_Definition_Source: Attribute: Attribute_Label: NAME Attribute_Definition: Name of Hydrologic Cataloging Units (Basin name) Attribute_Definition_Source: U.S. Geological Survey, OWDC (Data originally in file HUC250.NAMES) Attribute_Domain_Values Enumerated_Domain Enumerated_Domain_Value: Oalphanumeric characters Enumerated_Domain_Value_Definition Enumerated_Domain_Value_Definition_Source: Attribute: Attribute_Label: DNRBASIN Attribute_Definition: Major River Basin as Designated by Georgia Department of Natural Resources Attribute_Definition_Source: Georgia Department of Natural Resources, Environmental Protection Div. 1995 Attribute_Domain_Values Enumerated_Domain Enumerated_Domain_Value: 30 Characters (14 unique basins) Enumerated_Domain_Value_Definition Enumerated_Domain_Value_Definition_Source: Entity_Type Entity_Type_Label: HUC250.AAT Entity_Type_Definition: HYDROLOGIC UNIT LINEWORK Entity_Type_Definition_Source: GIRAS DATA Attribute: Attribute_Label: ' FNODE#' Attribute_Definition: Internal number of from-node Attribute_Definition_Source: Computed Attribute_Domain_Values Enumerated_Domain Enumerated_Domain_Value: Sequential unique positive integer Enumerated_Domain_Value_Definition Enumerated_Domain_Value_Definition_Source: Attribute: Attribute_Label: ' TNODE#' Attribute_Definition: Internal number of to-node Attribute_Definition_Source: Computed Attribute_Domain_Values Enumerated_Domain Enumerated_Domain_Value: Sequential unique positive integer Enumerated_Domain_Value_Definition Enumerated_Domain_Value_Definition_Source: Attribute: Attribute_Label: ' LPOLY#' Attribute_Definition: Internal number of polygon to left of arc Attribute_Definition_Source: Computed Attribute_Domain_Values Enumerated_Domain Enumerated_Domain_Value: Sequential unique positive integer Enumerated_Domain_Value_Definition Enumerated_Domain_Value_Definition_Source: Attribute: Attribute_Label: RPOLY# Attribute_Definition: Internal number of polygon to right of arc Attribute_Definition_Source: Computed Attribute_Domain_Values Enumerated_Domain Enumerated_Domain_Value: Sequential unique positive integer Enumerated_Domain_Value_Definition Enumerated_Domain_Value_Definition_Source: Attribute: Attribute_Label: LENGTH Attribute_Definition: Length of arc in coverage units Attribute_Definition_Source: Computed Attribute_Domain_Values Enumerated_Domain Enumerated_Domain_Value: Positive real numbers Enumerated_Domain_Value_Definition Enumerated_Domain_Value_Definition_Source: Attribute: Attribute_Label: HUC250# Attribute_Definition: Internal feature number Attribute_Definition_Source: Computed Attribute_Domain_Values Enumerated_Domain Enumerated_Domain_Value: Sequential unique positive integer Enumerated_Domain_Value_Definition Enumerated_Domain_Value_Definition_Source: Attribute: Attribute_Label: HUC250-ID Attribute_Definition: User-assigned feature number Attribute_Definition_Source: User-defined Attribute_Domain_Values Enumerated_Domain Enumerated_Domain_Value: Integer Enumerated_Domain_Value_Definition Enumerated_Domain_Value_Definition_Source: Attribute: Attribute_Label: SOURCE Attribute_Definition: LINE CODING FOR UNIQUE CASES Attribute_Definition_Source: GIRAS AND 1:2M DLG DATA Attribute_Domain_Values Enumerated_Domain Enumerated_Domain_Value: 1=100K 2=250K 3=250K EDGE 4=2MILLION DLG Enumerated_Domain_Value_Definition Enumerated_Domain_Value_Definition_Source: Overview_Description Entity_and_Attribute_Overview For definition of drainage basins, there are two principal tabular data elements of interest. The first, "HUC", stands for the Hydrologic Unit Code and includes the 8-digit cataloging unit as assigned to the basin polygon by the U.S. Geological Survey. The second item, "SOURCE", is an attribute of each bounding line segment (arc) and incorporates a code to define the source and scale of the source linework. Because this data set includes linework from different scale sources, it is important to recognize the presence and use of this item in quality evaluation. The SOURCE item has four special codes to describe the source linework. Code 1 stands for all arcs that were from 1:100,000 scale GIRAS files and were internal to the quadrangle (no neatlines). Code 2 stands for all arcs from the 1:250,000-scale GIRAS files which were internal to the quadrangle. Code 3 is for lines from either GIRAS source scale but were part of the neatline which may be used to connect arcs that dont join cleanly between quads. Code 4 is for linework in the southern Central Valley and southern Coastal California where the GIRAS data were replaced with 1:2 million scale basin boundaries. The NAMES item derived from a join between the PAT and the file HUC250.NAMES provides the hydrologic cataloging unit name or basin name. Entity_and_Attribute_Detail_Citation: Not Available --------------------------------------------------------------------------- Distribution_Information Distributor Contact_Person_Primary Contact_Person: Jonathan W. Musser Contact_Organization: U.S. Geological Survey Contact_Position: Hydrologist Contact_Address Address_Type: mailing address Address: U.S. Geological Survey 3039 Amwiler Road Suite 130 City: Atlanta State_or_Province: GA Postal_Code: 30360-2824 Country: USA Contact_Facsimile_Telephone: 770-903-9199 Contact_Electronic_Mail_Address: jwmusser@usgs.gov Standard_Order_Process Digital_Form Digital_Transfer_Information Format_Name: ARCE ARC/INFO Export format File_Decompression_Technique: gzip Format_Name: SDTS Spatial Data Transfer Standards (FIPS 173) File_Decompression_Technique: gzip & tar Digital_Transfer_Option Online_Option Computer_Contact_Information Network_Address Network_Resource_Name: http://csat.er.usgs.gov/statewide/layers/huc250.html --------------------------------------------------------------------------- Metadata_Reference_Section Metadata_Date: 19980109 Metadata_Contact: bdmoudry Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata Metadata_Standard_Version: 19940608 Metadata_Time_Convention: Local Time Metadata_Security_Information: Metadata_Security_Classification_System: None Metadata_Security_Classification: UNCLASSIFIED Metadata_Security_Handling_Description: None --------------------------------------------------------------------------- Last modified: 2008-03-20